A. Field
The present invention relates to a method and system for powering electric drive motors of a group of at least two machines wherein the drive motors operate in periodic motions and receive their power from at least one electric power source.
B. Related Art
Machines operating in periodic motions illustratively may be weaving machines containing several components which move in a predetermined, repetitive manner. For instance one such component is a reed which is driven at given times in one and then the other direction. Such components also include shed forming means which are moved up and down at given times. Further such components include—with respect to gripper looms, for instance—grippers and their drive elements moving said grippers at given times into and then out of a shed. When several such components are driven by a drive motor in such a periodically recurring sequence of motions, the drive motor also moves in a repetitive or periodic motion. As regards weaving machines, the period of said motion is defined by the number of weaving cycles making up one weaving pattern. A weaving pattern is the manner in which warps and fillings are interwoven in accordance with a repeat pattern. The periodic displacement of the individual components generally results in periodic variation of the power being fed from a supply system to the drive motor. This periodic variation of power is required so that the angular speed of the drive motor will vary only within narrow limits. Accordingly the power applied to the drive motor of a weaving machine will vary between a minimum and a maximum value. Consequently the power applied from such a power source to the drive motors of a group of weaving machines shall also vary. As a result such a power source must be able the feed the sum of the maximum values of the power required by the drive motors of a group of weaving machines. Therefore an expensive power source is required which, on account of the variable power being applied, operates at low efficiency and resulting high operating costs. Therefore an expensive power source is required which, on account of the variable power being applied, operates at low efficiency and resulting high operating costs.
As regards a combing machine comprising several synchronously driven shafts each fitted with individual electrical drives, it is known from the German patent document 195 09 209 A1 to fit a first drive motor with a measured-position pickup connected to a control unit. Based on the first drive's measured position values, the control unit establishes position setpoints for the remaining drives.